Polymers that have long branches (i.e., long enough to become entangled with other polymer strands) have qualitatively different flow behavior than those which are purely linear, and this profoundly affects the processing and crystallization of these polymers. It is often desirable to incorporate an amount of polymers having long-chain-branching (LCB) into polymers to achieve particular processability and properties. Dendritic polymers can be very useful in this regard, but their synthesis can be laborious and expensive.
While LCB technology has been a part of the polyethylene industry for some time, there is still a need to further optimize the type and availability of LCB polyethylenes and other polymers. A useful, inexpensive blend additive in the form of a LCB polymer could significant impact the processing/performance balance for polyethylenes, particularly the multi-billion dollar market for polyethylene films and molded articles. There could be even greater use in polypropylene, where there is currently little commercially viable technology for incorporating LCB.
Conventional polyethylenes, such as LDPE produced via high pressure free radical polymerization, typically exhibit a broad distribution of LCB. With the advent of metallocenes and other single-site coordination catalysts, there have been some products containing smaller amounts of LCB (such as Enable from EMCC, and Elite from The Dow Chemical Company).
A synthetic method used to prepare dendritic polyethylene is the anionic condensation method followed by hydrogenation. It involves four synthetic steps; synthesis of initiator precursor, initiation, anionic polymerization, and polycondensation. This synthesis has extremely low tolerance to impurities and can be stopped with the accumulation of impurities in the reactor.
It would be desirable to have a simpler and more versatile process for producing dendritic LCB polymers. It would be further desirable to have a simpler and more versatile process for producing dendritic LCB olefins.
The present disclosure also provides many additional advantages, which shall become apparent as described below.